This application requests a further five years of support for an Institutional National Research Service Award to support multidisciplinary training in drug abuse research. We request support for seven post-doctoral fellows (2-3 MDs and 4-5 PhDs) per year for primary training in (i) genetics (statistical/ quantitative, behavioral or molecular), (ii) neurobiology and molecular biology of substance use disorders, (iii) epidemiology and nosology of drug abuse and its role in the transmission of HIV and infectious diseases. In addition to specialization in a primary discipline, trainees are encouraged to obtain a sufficient familiarity with at least one other focus area to facilitate fruitful cross-disciplinary collaborations in their research careers. The training program will ordinarily be of 3 years duration, reflecting the diverse background of our applicant pool (e.g. psychiatry, infectious diseases, mathematics, chemical engineering, biostatistics, neurobiology, molecular genetics, social work, sociology, anthropology, psychology, economics, neuroscience), or 2 years for those with pertinent research experience. One-year post-doctoral fellowships are also offered for experienced drug abuse researchers seeking training in a new area of drug abuse research (e.g. genetics). Trainees are housed in specially designed post-doctoral offices in the Psychiatry section of the University's Biotechnology Center and in the laboratory facilities of the Clinical Sciences Research Building. The program emphasizes a research apprenticeship model in combination with formal training through didactic courses and individualized tutorials. Major strengths of the program are the expertise of the faculty in genetic, epidemiologic and nosologic, molecular biologic and neurobiologic research on substance use disorders (including HIV-related research), the long tradition of successful research training of individuals from diverse backgrounds, the highly productive research environment (with the preceptors holding a total of 42 federally funded grants), and the access to major ongoing projects and to existing epidemiologic and family data-bases that offer many research possibilities to trainees.